1. Field of the Invention
The invention relates generally to image enhancement techniques, and more specifically to real-time image enhancement methods which are performed on textual and/or color photographic images.
2. Description of the Prior Art
Image enhancement is a process by which acquired image data values are manipulated. Such manipulation is typically directed to improving the appearance of the data as perceived by humans, and/or to render the data more suitable for machine analysis of the image. Image enhancement processes are distinguishable from image restoration processes in that one objective of restoration processes is to improve the fidelity and/or accuracy of a reproduced image with respect to the original image, whereas enhancement processes place greater emphasis on human visual perception and/or the suitability of the processed image for computer analysis.
Various image enhancement processes have been developed for improving the perceived clarity, intelligibility, and/or quality of images. These image enhancement processes attempt to render images more pleasing to human eyes, irrespective of whether or not these images are accurately reproduced. Oftentimes, a distorted image is more pleasing to the human eye than a perfectly reproduced copy of the original image. For example, if overshoot or undershoot is incorporated into the edges of an image, the resulting image is typically perceived as being more pleasing than an image without such undershoot or overshoot.
Many prior art image enhancement processes have focused on the improvement of gray-level images, but a direct extension of these processes into the color domain results in degraded or suboptimal images. At the present time, there is a notable lack of image enhancement techniques which are optimized for use in conjunction with color images. The widespread distribution of color images, the growing popularity of multimedia applications, the current proliferation of personal computing devices, and the development of high-definition television systems all serve to increase the demand for improved color image enhancement methods. Such image enhancement methods should be optimized for use in conjunction with color images, and should not merely constitute the reapplication of a gray-level method to the color domain. Moreover, such image enhancement methods should operate in real time using existing hardware platforms.
Although it is possible to enhance a color image by applying existing monochrome image enhancement algorithms to each color component (red, green, and blue) individually, the resulting image may not be enhanced optimally. Image distortion will result if the red, green, and blue components are not properly recombined after the monochrome image enhancement algorithms are applied. Moreover, image distortion will also result if the red, green, and blue components are processed independently, without considering correlation among the components.